AMSOIL vs. Mobil 1: Ultimate Synthetic Oil Showdown

The short answer

If your engine calls for a dexos® R 0W-40 — that includes the C8 Corvette, Cadillac V-Series, supercharged Camaro, and the post-recall GM 6.2L L87 — AMSOIL Signature Series 0W-40 (AZF) is dexos® R approved, publishes a measurable HTHS margin over the specification floor, and is engineered for the long drain intervals high-output engines actually run between services. AMSOIL is also approved for the Nissan GT-R and carries the Chrysler MS-A0921 SRT specification. Mobil 1’s Supercar and FS 0W-40 are dexos® R approved as well — the published spec data, AMSOIL’s own engine-test results, and the extended-drain coverage below are why more performance owners are switching.

National Synthetics is an Independent AMSOIL Dealer, and we stock AZF locally for our Georgia customers.

Why this comparison matters now

• The dexos® R standard is here. GM created dexos® R specifically for the C8 Corvette, Cadillac V-Series, and supercharged Camaro — high-output platforms whose oil-film and LSPI demands exceed dexos1® Gen 3.
• The GM 6.2L L87 recall makes 0W-40 mandatory. Roughly 800,000 Silverado, Tahoe, Suburban, Sierra, Yukon, and Escalade vehicles must move permanently to 0W-40 after the recall service.
• Performance owners are converging on 0W-40. Nissan GT-R, Chrysler SRT, and many supercharged builds all run a 0W-40 at operating temperature.

That puts a much sharper question in front of the buyer: which 0W-40?

Published physical and chemical properties

Every AMSOIL figure below is taken from the current AMSOIL Signature Series 0W-40 (AZF) data bulletin. Every Mobil 1 figure below is taken from each oil’s current published Product Data Sheet on mobil.com. Cells marked “Not published” reflect what the current Mobil 1 PDS does and does not list. Physical properties are typical values, not minimum/maximum specifications.

Property	AMSOIL Signature Series 0W-40 (AZF)	Mobil 1 Supercar 0W-40	Mobil 1 FS 0W-40
Kinematic Viscosity @ 100 °C (cSt)	14.8	12.9	13.8
Kinematic Viscosity @ 40 °C (cSt)	84.6	69.0	78.3
Viscosity Index	184	Not published	Not published
HTHS Viscosity @ 150 °C (cP)	3.76	Not published (3.5 dexos® R minimum)	Not published (3.5 dexos® R minimum)
Cold Cranking Simulator @ −35 °C (cP)	6,062	Not published	Not published
Pour Point (°C / °F)	−50 / −58	−51 / −60	−42 / −44
Flash Point — COC (°C / °F)	222 / 431	232 / 450	230 / 446
NOACK Volatility (% wt loss)	7.7	Not published	Not published
Total Base Number (mg KOH/g)	12.5	8.5	Not published
Phosphorus (% wt)	Listed in bulletin	0.09	Not published
dexos® R approval	Yes	Yes	Yes

Sources: AMSOIL Signature Series 0W-40 (AZF) data bulletin (amsoil.com / nationalsynthetics.com); Mobil 1 Supercar 0W-40 Product Data Sheet (mobil.com); Mobil 1 FS European Car Formula 0W-40 Product Data Sheet (mobil.com). Mobil 1 and Supercar are trademarks of ExxonMobil Corporation. dexos® is a registered trademark of General Motors.

What the numbers actually mean

Film strength (HTHS) decides what’s between your bearings

HTHS — High-Temperature High-Shear viscosity at 150 °C — is the load-bearing film-thickness number. It is the figure GM elevated when writing the dexos® R specification, and it is the property that protects rod bearings, cam lobes, and turbo journals when the oil is hot, sheared, and under load.

dexos® R sets a 3.5 cP minimum. AMSOIL Signature Series 0W-40 publishes 3.76 cP in its current data bulletin — a measurable, transparent margin above the floor. That margin is what you spend during a long climb at full throttle, on the second hour of a track day, or any time the engine is running near its design limits. Both Mobil 1 Supercar 0W-40 and Mobil 1 FS 0W-40 are dexos® R approved, so both clear the 3.5 cP minimum — Mobil 1 simply does not publish their typical HTHS value in the current PDS.

Cold-flow protection where the wear actually happens

Most engine wear happens in the first seconds after cold start, when oil pressure is still building. AZF publishes a −50 °C / −58 °F pour point and a Cold Cranking Simulator value of 6,062 cP at −35 °C. The oil is pumping to the bearings before the starter motor finishes cranking, even in deep winter conditions.

NOACK volatility — less burn-off, fewer deposits

NOACK measures how much oil evaporates under sustained heat. AZF publishes 7.7 %. Lower NOACK means three things owners actually feel: less oil consumption between top-ups, cleaner intake valves on direct-injection engines, and less risk of LSPI in turbocharged engines. Mobil 1 does not publish a NOACK value for the current Supercar or FS 0W-40 grades.

TBN drives drain interval

Total Base Number is the additive package’s reserve to neutralize acids before they attack bearings and rings. AZF publishes a TBN of 12.5, supporting AMSOIL’s published extended-drain interval. Mobil 1 Supercar 0W-40 publishes a TBN of 8.5. A higher TBN does not mean better protection day-one; it means the oil keeps protecting longer, which is the basis for AMSOIL’s drain-interval guarantee.

Spec transparency is itself a buying signal

Across the table above, AMSOIL publishes the full data bulletin — viscosity index, HTHS, CCS, NOACK, TBN, flash, pour, fire — in one place. Mobil 1’s current public PDS for these two 0W-40 grades omits HTHS, VI, NOACK, CCS, MRV, and (for FS) TBN. Both companies have those values internally; only AMSOIL publishes them all.

AMSOIL engine-test results vs. industry minimums

AMSOIL publishes the following Signature Series test results, run against the API SP and dexos1® Gen 3 industry-standard procedures. Figures are reported by AMSOIL.

Approvals and fitment matrix

Specification	AMSOIL Signature Series 0W-40 (AZF)	Mobil 1 Supercar 0W-40	Mobil 1 FS 0W-40
API SP	Yes	Yes	Yes
GM dexos® R	Yes	Yes	Yes
Nissan GT-R approved	Yes	—	—
Chrysler MS-A0921 (SRT)	Yes	—	—
Chrysler MS-12633	Yes	—	—
Chrysler MS-10725 / MS-10850	Yes	—	—
MB-Approval 229.5	—	—	Yes
MB-Approval 229.3	—	—	Yes
Porsche A40	—	—	Yes
VW 502 00 / 505 00	—	—	Yes
BMW Longlife 01	—	—	Yes
ACEA A3/B4	—	—	Yes

A dash (—) means the manufacturer does not publicly list that approval for that oil at the time of this publication. Read this matrix honestly: for North American performance applications — dexos® R, Nissan GT-R, and Chrysler SRT — AMSOIL Signature Series 0W-40 is the matched answer. For European OEM service that strictly requires a Mercedes-Benz, Porsche, VW, or BMW Longlife formal approval on the bottle, Mobil 1 FS 0W-40 carries those approvals. Always confirm against the current data bulletin and your owner’s manual before service.

Use-case guidance

C8 Corvette, Cadillac V-Series, supercharged Camaro

These platforms specifically call for a dexos® R 0W-40. AMSOIL Signature Series 0W-40 (AZF) is dexos® R approved and publishes the HTHS margin and NOACK numbers shown above — both of which matter on a track day where the LT2/LT4/LT6 will see sustained 300 °F oil temps.

GM 6.2L L87 recall (Silverado, Tahoe, Suburban, Sierra, Yukon, Escalade)

After the recall service, GM permanently mandates 0W-40. AZF satisfies that requirement and AMSOIL specifically lists the GMC Sierra 6.2L L87 as a recommended application. See the full GM 6.2L V8 recall guide for VIN-check links and step-by-step service guidance.

Nissan GT-R (VR38DETT)

Twin-turbocharged 0W-40 service has been GT-R doctrine since the R35 launched. AMSOIL specifically lists Signature Series 0W-40 (AZF) as approved for the Nissan GT-R. The 7.7 % NOACK and 3.76 cP HTHS line up well with the VR38DETT’s load profile.

Chrysler SRT (Hellcat, Demon, Trackhawk, TRX)

Chrysler’s high-output SRT engines call for an MS-A0921 0W-40. AZF carries the Chrysler MS-A0921, MS-12633, MS-10725, and MS-10850 approvals — the right answer when you’re filling a supercharged Hemi or a TRX.

European OEM service (Porsche, Mercedes-Benz, VW, Audi, BMW)

If your owner’s manual requires a formal Porsche A40, MB 229.5, VW 502 00/505 00, or BMW Longlife 01 approval printed on the bottle, Mobil 1 FS 0W-40 carries those approvals. AMSOIL doesn’t currently list these European factory approvals on the AZF bulletin — we’d rather tell you that up front than push the wrong product.

Supercharged or modified builds

Boost adds heat. Heat shears VI improvers and breaks marginal additive packages. AZF’s published TBN of 12.5 and Sequence IIIH result point to additive durability that holds up under aftermarket power.

Extended drain intervals — the part Mobil 1 doesn’t claim

AMSOIL guarantees Signature Series for up to 25,000 miles or one year in normal personal-vehicle service, and 15,000 miles or one year in severe service (commercial, towing, dusty conditions, frequent idling). That coverage is in writing, not implied. Mobil 1’s 0W-40 grades are sold for normal OEM-interval service.

For owners who put real miles on a performance car or fleet truck, the math favors AMSOIL even before you factor in the Preferred Customer wholesale pricing.

Frequently Asked Questions

Which 0W-40 synthetic oils carry the GM dexos® R approval?

GM dexos® R is the high-performance specification used for the C8 Corvette, Cadillac V-Series, supercharged Camaro, and the updated 6.2L L87 recall remedy. AMSOIL Signature Series 0W-40 (AZF), Mobil 1 Supercar 0W-40, and Mobil 1 FS 0W-40 are all dexos® R approved. AMSOIL adds extended-drain capability on top of the same approval.

How does AMSOIL Signature Series 0W-40 compare to Mobil 1 0W-40 on HTHS viscosity?

High-Temperature High-Shear (HTHS) viscosity at 150°C is the load-bearing film-strength number. AMSOIL Signature Series 0W-40 publishes an HTHS of 3.76 cP, well above the dexos® R 3.5 cP minimum. Mobil 1's current Supercar and FS 0W-40 product data sheets do not publish an HTHS value, but every dexos® R approved oil meets at least 3.5 cP by definition.

Will AMSOIL Signature Series 0W-40 satisfy the GM 6.2L L87 recall remedy?

Yes. GM's recall remedy requires a dexos® R approved 0W-40 synthetic. AMSOIL Signature Series 0W-40 (AZF) is dexos® R approved and meets the post-recall oil specification. Read the full GM 6.2L recall guide for details.

Is AMSOIL Signature Series 0W-40 approved for the Nissan GT-R?

Yes. AMSOIL specifically lists Signature Series 0W-40 (AZF) as approved for the Nissan GT-R VR38DETT engine. As always, document the change with receipts to protect warranty coverage under the Magnuson-Moss Warranty Act.

What is the NOACK volatility of AMSOIL Signature Series 0W-40?

AMSOIL Signature Series 0W-40 publishes a NOACK volatility of 7.7 percent. Lower NOACK means less oil burn-off in hot, high-load operation, which reduces oil consumption and helps keep intake valves and turbo bearings cleaner over time. Mobil 1's current Supercar and FS 0W-40 product data sheets do not publish a NOACK value.

Why does viscosity index matter in a 0W-40 performance oil?

Viscosity Index (VI) measures how stable an oil's viscosity stays across the temperature range. AMSOIL Signature Series 0W-40 publishes a VI of 184 — meaning the oil thins less when hot and thickens less when cold. That protects bearings during cold starts and keeps film thickness intact at sustained track temperatures. Mobil 1 does not publish a VI for the current Supercar or FS 0W-40 grades.

How long can I safely go between oil changes on AMSOIL Signature Series 0W-40?

AMSOIL guarantees Signature Series for up to 25,000 miles or one year in normal personal-vehicle service, and 15,000 miles or one year in severe service (commercial, towing, dusty, frequent idling). Always honour the OEM service interval if it is shorter — particularly during a manufacturer warranty period. See our oil change interval guide.

Can I switch from Mobil 1 0W-40 to AMSOIL 0W-40 without flushing?

Yes. AMSOIL Signature Series 0W-40 is fully compatible with other API-licensed and dexos® R approved synthetic 0W-40 oils. No flush is required. Drain the old oil at temperature, replace the filter, and fill with AMSOIL.

Does using AMSOIL instead of the dealer-supplied Mobil 1 void my GM warranty?

No. The Magnuson-Moss Warranty Act prohibits manufacturers from voiding a warranty solely because you use a qualifying aftermarket lubricant. As long as the oil meets the required specification — for example, dexos® R 0W-40 — your warranty stays intact. Keep your purchase receipts and oil-change records.

Where can I buy AMSOIL Signature Series 0W-40 through National Synthetics?

Order direct from AMSOIL.com using our dealer link for ship-direct or local pickup. Becoming an AMSOIL Preferred Customer unlocks wholesale pricing on every reorder.

Recommended AMSOIL Products

Talk to your local AMSOIL dealer

National Synthetics has been supplying AMSOIL products to Georgia performance owners, fleets, and shops for over a decade. If you’re not sure which 0W-40 your OEM is calling for — or you want to confirm dexos® R fitment before you order — call us.

Phone: 1-678-944-8816
Dealer #: 1858536
Order direct: AMSOIL Signature Series 0W-40 (AZF)

Related reading

• Dexos® R ushers in a new motor oil standard for high-performance engines
• GM 6.2L V8 engine recall: the crankshaft crisis and why switching to 0W-40 oil matters
• Understanding oil viscosity
• Understanding engine oil specifications
• AMSOIL oil change interval guide
• Why buy AMSOIL Signature Series

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Mobil 1, Supercar, FS, and the Mobil 1 trade dress are trademarks of ExxonMobil Corporation. Dexos is a registered trademark of General Motors. Porsche, Mercedes-Benz, Volkswagen, Audi, BMW, Nissan, GT-R, Chrysler, and SRT marks are the property of their respective owners. National Synthetics is an Independent AMSOIL Dealer and is not affiliated with ExxonMobil, General Motors, or any vehicle manufacturer named in this article. All product specifications are taken from each manufacturer’s current published Product Data Bulletin or Product Data Sheet and are subject to change without notice — always confirm against the current data bulletin and your owner’s manual before service.